EPDM membranes, which are cured sheets of ethylene-propylene-diene terpolymer rubber, are often used in the construction industry to cover flat or low-sloped roofs. During manufacture of the EPDM membranes, uncured sheets, also referred to as green membranes, are rolled and placed into a curing oven to effect vulcanization of the rubber in the presence of a cure system. In order to prevent the roll of green membrane from sticking to itself (“blocking”), and ultimately curing to itself, the membrane is treated with a dusting agent or particulate prior to being rolled and cured. Industry standards include the use of talc and mica for dusting, although other materials have been used such as, for example, cellulosic materials. After curing of the membrane, the rolled, cured membrane is unrolled, typically within a stripping operation, and then fabricated into a roofing membrane. Fabrication may include, for example, cutting the membrane to size or applying an adhesive tape.
These membranes, which may also be referred to as panels, are typically delivered to a construction site in a bundled roll, transferred to the roof, and then unrolled and positioned. The sheets are then affixed to the building structure by employing varying techniques such as mechanical fastening, ballasting, and/or adhesively adhering the membrane to the roof. The roof substrate to which the membrane is secured may be one of a variety of materials depending on the installation site and structural concerns. For example, the surface may be a concrete, metal, or wood deck, it may include insulation or recover board, and/or it may include an existing membrane.
In addition to securing the membrane to the roof—which mode of attachment primarily seeks to prevent wind uplift—the individual membrane panels, together with flashing and other accessories, are positioned and adjoined to achieve a waterproof barrier on the roof. Typically, the edges of adjoining panels are overlapped, and these overlapping portions are adjoined to one another through a number of methods depending upon the membrane materials and exterior conditions. The overlapped portions are often referred to as lap regions. One approach to seaming the membranes involves providing adhesives or adhesive tapes between the overlapping portions, thereby creating a water resistant seal.
Where adhesives are employed to seam the membranes to each other (i.e., create a lap seam) and/or adhere the membrane to the roof surface, the presence of the dusting agent, which may also be referred to as particulate, can be problematic since the dusting agent can interfere with proper adhesion between the membrane and the adhesive. As a result, steps must be taken to remove the dusting agent in the location where the adhesive is applied. For example, known techniques for lap seam preparation include the use of a primer solution in conjunction with a scrubbing apparatus that can lift the dusting agent away from the membrane by, for example, employing scrubbing techniques. Similar issues exist where there is a desire to create a fully-adhered roofing system wherein adhesive is used to secure substantially one surface of a membrane panel to the roof deck. Typically, where there is a desire to create a fully-adhered roofing system, thick layers of adhesive, or multiple layers of adhesive, including those adhesives that are dissolved in organic solvents, are used to adhere the membranes that carry the dusting agent. Still further, the presence of the dusting agent can frustrate further fabrication or modification of the membranes. For example, where there is a desire to adhere a fabric backing to the EPDM sheet, such as a fleece backing, the presence of the dusting agent can frustrate the adherence of the fabric to the membrane. Also, where there is a desire to prepare an EPDM membrane carrying a factory-applied adhesive layer (e.g., a peel-and-stick membrane), the presence of the dusting agent can interfere with proper application and adhesion of the pressure-sensitive adhesive to the membrane surface.